Problem: The grades on a chemistry midterm at Oak are normally distributed with $\mu = 69$ and $\sigma = 3.0$. Tiffany earned a $70$ on the exam. Find the z-score for Tiffany's exam grade. Round to two decimal places.
Answer: A z-score is defined as the number of standard deviations a specific point is away from the mean We can calculate the z-score for Tiffany's exam grade by subtracting the mean $(\mu)$ from her grade and then dividing by the standard deviation $(\sigma)$ $ { z = \dfrac{x - {\mu}}{{\sigma}}} $ $ { z = \dfrac{70 - {69}}{{3.0}}} $ ${ z \approx 0.33}$ The z-score is $0.33$. In other words, Tiffany's score was $0.33$ standard deviations above the mean.